A recent significant advancement in the field of generating low temperature refrigeration is the pulse tube and other cryocooler systems wherein pulse energy is converted to refrigeration using an oscillating gas. Such systems can generate refrigeration to very low levels sufficient, for example, to liquefy helium.
One problem with conventional cryocooler systems is the loss of effective load heat capacity and flow uniformity and the resulting heat transfer maldistribution in the regenerator portion of the cryocooler which leads to operational inefficiency. These problems are particularly troublesome when the cryocooler is operated to provide very low temperature refrigeration such as below 40K.